Satellite and ground-based observations from March 28 to 29, 1992, were combined in the assimilative mapping of ionospheric electrodynamics (AMIE) procedure to derive realistic global distributions of the auroral precipitation and ionospheric convection which were used as inputs to the National Center for Atmospheric Research (NCAR) thermosphere-ionosphere general circulation model (TIGCM). Comparisons of neutral model winds were made with Fabry-Perot measurements and meridional winds derived from ionosondes. The peak equatorward winds occurred 1--2 hours later in the model. Gravity waves launched from high-latitude Joule heating sources reached the equator in about 2 hours and agreed with observed variations in the height of the maximum electron density (hmF2) and in the meridional winds. Joule heating events produced minima in the O/N2 ratio that moved equatorward and usually westward in longitudinal strips which lasted about a day. Changes in the O/N2 ratio and in the peak electron density (NmF2) were strongly correlated so the observed daytime NmF2 values for stations near 50¿ magnetic latitude were generally reproduced by AMIE-TIGCM on the second day of the simulation. The AMIE-TIGCM underestimated the electron density after midnight by up to a factor of 2 in midlatitudes, while the modeled F2 layer was about 35 km lower than the observations at midnight. Shifting the model winds 2 hours earlier at night could double the NmF2 at 0400 LT and increase hmF2 by 20 km. NmF2 could also be increased at night by realistically increasing the TIGCM nighttime downward fluxes of O+ at the upper boundary. ¿ American Geophysical Union 1996